The invention relates to an apparatus for needling a non-woven material with at least one needleboard which is drivable in a reciprocating manner by at least one eccentric drive in the needle-penetration direction, which needleboard is linked to the eccentric drive via push rods each displaceably held in a guide sleeve, which eccentric drive consists of two parallel eccentric shafts which are drivable in opposite directions and are provided with connecting rods, with the guide sleeves being swivelably held about an axle extending parallel to the eccentric shafts.
In order to increase the advance of the non-woven material at a compact construction it is known (DE 199 10 945 A1) to link the needleboard to an eccentric drive via push rods which are each displaceably held in a guide sleeve, which eccentric drive consists of two parallel eccentric drives which are drivable in opposite directions and are provided with connecting rods, with the guide sleeves being swivelably held about an axle extending parallel to the eccentric shafts, so that the guide sleeves can be swiveled for an additional drive of the needleboard in the direction of advance of the non-woven material. A further eccentric drive is used for driving the guide sleeves, which eccentric drive comprises on its part two eccentric shafts. The connecting rods of said eccentric shafts are connected to a coupler, to which a guide arm is linked which is rigidly connected with the guide sleeves. Since the stroke of the point of articulation of the guide arm on the coupler depends on the coupling movement and thus the mutual phase position of the two eccentric shafts in the case of given eccentricities, the swiveling stroke for the guide sleeves can be set via a device for adjusting the mutual angular position of the eccentric shafts. Despite the possibility achieved by this construction to keep the connecting rods of the eccentric drive short for the needleboard movement in the direction of advance of the non-woven material and thus to house said eccentric drive in a common housing with the main drive, there is a respective amount of constructional effort involved in the additional eccentric drive for driving the needleboard in the direction of advance of the non-woven material.
The invention is thus based on the object of providing an apparatus for needling a non-woven material of the kind mentioned above with simple constructional means in such a way that a considerable constructional simplification is ensured without having to make do without a needleboard drive in the direction of advance of the non-woven material.
This object is achieved by the invention in such a way that the two eccentric shafts are provided with a different angular position and that the connecting rods of the two eccentric shafts extend in an inclined manner with respect to each other.
Since the connecting rods of the two oppositely drivable eccentric drives for the needleboard drive in the needle-penetration direction are not provided, as is otherwise usual, with a central position extending in the needle-penetration direction but extend inclined in opposite directions with respect to the needle-penetration direction, the needleboard can be driven along an inherently closed trajectory by a phase shift between said two eccentric drives, because the push rods are swiveled with the guide sleeves about the swiveling axis of the guide sleeves via the connecting rods when a respective forced guidance of the connecting rods is ensured.
This forced guidance can be ensured in a simple way when arranging the needleboard in such a way that the connecting rods act upon the push rods via coaxial link axles. The needleboard drive in accordance with the invention can also be extended to two needleboards arranged successively in the direction of the advance of the non-woven material which needleboards are each driven via push rods held in swivelable guide sleeves by a common eccentric drive. In this case the push rods of the two needleboards must be coupled via a coupler on which act the push rods of the eccentric shafts. The coupler needs to be guided in addition in order to achieve the forced guidance of the connecting rods of the two eccentric shafts. For this reason the coupler is held in a lifting guide means and in a middle position extending in the direction of the needle penetration is swiveled about an axis parallel to the eccentric shafts. This lifting guidance allows the lifting movement of the coupler which is required for the needleboard drive in the needle-penetration direction, which coupler swivels out as a result of its design transversally to the penetration direction during the penetration stroke as a result of its additional swiveling bearing and thus ensures a respective swiveling displacement of the push rods which are held in the guide sleeves. A displacement guide means can be provided as a lifting guide means, which displacement guide means is held in a manner so as to be swivelable about an axle parallel to the eccentric shafts. Another embodiment of the lifting guide means is to link the coupler at least to one transverse link extending transversally to the needle-penetration direction. A respective four-bar linkage can be used to achieve a straight guidance of the linkage axle between coupler and lifting guide means when symmetrical conditions are required for both needleboard drives.
In order to enable the setting of the needleboard stroke in the direction of the advance of the non-woven material during a needling process, it is merely necessary to displace the two eccentric shafts in their mutual angular position, which can be achieved very easily from a constructional viewpoint.